Evolution of the Quantum Theory

Abstract

The great new reformulation of quantum theory, which we know today as quantum mechanics, occurred mostly in 1925 and 1926. I shall not attempt to deal with the events of the past few years, on the ground that it is too soon to try to see them in historical perspective. But so great was the range of subject matter opened up for physics in the quantum-theoretical problems of the period 1925--40, that I shall have difficulty in even taking the barest notice of them in a short article.